1. (Field of the Invention)
The invention relates to a nozzle plate adapted for an ink jet recording apparatus and a method of preparing such nozzle plate. More particularly, it is directed to a nozzle plate on which a water-repellent coating is provided on both the front surface of the nozzle plate and on the inner surface of the nozzles and to a method of preparing such nozzle plate.
2. (Prior Art)
An ink jet printer has a problem that when a portion around a nozzle is wetted by an ink, the direction of splashing ink droplets deviates. To overcome this problem, Japanese Patent Unexamined Publication No. 65564/1980 or 55140/1990 has proposed an art that contributes to suppressing generation of such wetting by the ink while providing a water-repellent coating on the surface of the nozzle plate.
However, to form such a coating, the rear surface of the nozzle plate must be masked to facilitate adhesion of an adhesive. With nozzle holes having been arranged on a member to be coated, it is difficult to cover a portion around the holes completely. Under such circumstances, part of the water-repellent coating provided on the front surface is extended into the inner surfaces of the nozzle holes unevenly, making the ink meniscuses to be formed inside the respective nozzle holes to be different from one nozzle hole to another and disadvantageously causing variations in ink jetting timing.
Further, a technique in which a coating material is embedded in each nozzle hole completely so that a water-repellent coating is provided only on the front surface of the nozzle plate causes the coating to form an edge-like protrusion around the rim portion of each nozzle hole. Thus, when such rim portion is wiped, the edge-like protrusion is chipped off, making the wettability locally different with resultant inconsistent ink splashing directions.
Still further, the provision of the water-repellent film only on the front surface of the nozzle plate causes inconsistent affinity at the exit of each nozzle hole, making the meniscus position unstable.
An object of the invention is to provide a novel nozzle plate that does not cause variations in both the direction of splashing ink droplets and the timing of jetting the ink droplets.
To achieve the above object, the invention is applied to a nozzle plate in which not only the front surface of the nozzle plate but also the inner surface of each nozzle hole are provided with a water-repellent coating uniformly.
Another object of the invention is to allow the meniscus of an ink to be formed more stably inside each nozzle hole.
To achieve this object, the invention is applied to a nozzle plate in which the water-repellent coating extending from the front surface of the nozzle plate to the inner surface of each nozzle plate is further extended to a portion around the ingress of each nozzle hole.
Still another object of the invention is to propose a novel method of forming a coating on a nozzle plate in which a water-repellent coating is formed uniformly from the portion around the ingress of each nozzle hole not only to the inner surface of the nozzle hole but also to the front surface of the nozzle plate.
To achieve this object, the invention is applied to a method comprising the steps of: providing a coating on the rear surface of a nozzle plate with a coating material excluding each nozzle hole and a portion around such nozzle hole to thereby form a uniform water-repellent coating on the front surface of the nozzle plate, the inner surface of each nozzle hole contiguous to the front surface, and the portion around the nozzle hole contiguous to the rear surface of the nozzle plate.